[WCM] Added shortcut methods for controllers

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no 
| Applies to    | master
| Fixed tickets | None

This is my first contribution to Symfony so I think everything may not be perfect. For instance, I did not know if I had to use versionadded since I don't know if it will be added soon or if I should include the PR on symfony/symfony to fixed tickets...

This commit is associated to https://github.com/symfony/symfony/pull/11593 that adds new shortcut methods to controllers.

If anything is wrong with my commit or this description, please tell me and I will fix it as soon as possible. I'm glad I finally try to help this awesome project.

You can link directly to the API docs (instead of ``redirectToRoute()``):

```rst
:method:`Symfony\\Bundle\\FrameworkBundle\\Controller::redirectToRoute``
```